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Abstract

Arthur’s Pass township, located close to the Main Divide of the central Southern Alps, is highly exposed to natural hazards and has been affected by hazard events since it was founded in 1906. The village is a small alpine township, with a permanent resident population of approximately 54. Its location within the Arthur’s Pass National Park and on the main road between the east and west coasts of the South Island makes it popular with tourists, trampers, climbers and skiers, which can expand the local population to up to 500 people. Its position on the Bealey River floodplain within a highly dynamic tectonic and geomorphic environment makes it vulnerable to earthquakes, landslides, rockfalls, debris flows, heavy rain and snow, river flooding and riverbed erosion.

Previous investigations on natural hazards in the area are limited to the Otira Gorge and State Highway 73, with little focus on hazards affecting the village area. Natural hazard events are persistent and frequent in the Arthur’s Pass region and the village is susceptible to being isolated from external resources during and after a disaster, making it necessary for the village to be self-sufficient during a large-scale disaster.

The hazards were identified and analysed using aerial photographs and satellite images, historical data, supported by in-field reconnaissance at various times of the year to record seasonal changes. Hazard mapping used the same methods to illustrate the spatial and volumetric hazard changes over a range of time scales; >2% annual probability of occurrence (0-50 years recurrence interval), 2%-0.2% annual probability of occurrence (50-500 years recurrence interval) and <0.2% annual probability of occurrence (500+ years recurrence interval). The hazard maps show that that most hazards are not restricted to a specific temporal or spatial scale, and that they are often interdependent.

It is difficult to determine the precise effects that climate change and global warming will have on natural hazards, but they are expected to increase the unpredictability of hazard events and alter weather patterns significantly in the long-term.

A visitor questionnaire undertaken in the village indicated that many visitors do not regard the hazards as severe enough to represent a legitimate threat; hence the public perceptions of natural hazards are affecting the vulnerability of the village. Additionally, many people do not feel confident that they would know what to do if a disaster did occur in the village. This level of awareness can be improved by providing more information to visitors and displaying details on emergency procedures.

The village does not currently have an emergency plan that specifies particular preparedness and response procedures; it relies heavily on a plan adapted from Mt. Cook/Aoraki village. Current emergency management in the village could be improved by the production of an emergency plan specifically for the region, the use of education schemes and information sessions, and the installation of warning signs.

The provision of this detailed hazard investigation and hazard maps is intended to assist emergency managers to identify, prioritise, mitigate the hazards to reduce the vulnerability of the village to natural hazards in the short- and long-terms.

Contains

Also available through inter-library loan are three large maps which have not been digitized.